Kazakh government has promised to ask "leading international medical institutions" to get involved in the tests to establish the cause of a mysterious ailment that has stricken villages near a uranium mine and an oil field in Kazakhstan.

Kazakh officials on January 13 discussed the results of investigations into the situation in the village of Kalachi near an abandoned uranium mine in northern Aqmola region.

Residents there have suffered somnolence, loss of memory, and hallucinations since March 2013.

Dozens of residents of another village, Beryozovka, located near a large oil field in Kazakhstan's west have suffered from fainting spells since November 2014.

Deputy Prime Minister Berdibek Saparbaev said air samples from both sites will be tested and sent to foreign medical institutions for analyses as well to have "an independent opinion."

The Astana-based National Medical Center said on January 12 that examinations of four patients from Kalachi revealed "no external factors that might have affected their health."